#include<stdio.h>

int main()
{
  FILE *fp=fopen("log.txt","a");
  if(NULL==fp)
  {
    perror("fopen");
    return 1;
  }
   


  fprintf(fp,"helloworld,%d,%s,%lf\n",10,"zero",3.14);

  fclose(fp);
  return 0;
}
